Setting up RAID

Snape, RAID 0 is NOT a RAID in strict sense. It just scatters (I hope it's the right word) your data onto 2 or more hard disks, speeding up your reads dramatically but also increasing (dramatically) your chances of data loss. If you want a RAID, RAID 1 (mirroring) is the least expensive way of doing it.

 

"Striping"

 

Well "Striping" may indeed be correct technical word, but what it is doing basically is scatterring the data all over the hard disk(s).

 

Yeah I know, that's what I wanted.

 

I read those links posted previously - very useful, thanks for those.
How about if I setup a RAID 3 or RAID 5? These will give increased performance without the risk in a RAID 0 right?

My main objective is to have increased read speeds with my hdd.

 

Go for RAID 1 (mirrorring). very fast read speeds but lousy writes.

 

With modern hard drives being so big, RAID 1 has a lot going for it. Simple to set up. Easy disaster recovery. I think that is your best bet.

RAID 3 has been superceded by RAID 5. You'll find it hard to find a controller that will support RAID 3.

RAID 3 is like RAID 0, but adds an additional disk to the array to hold parity information, which allows the data to be retrieved if a disks breaks. You can think of it working like A + B = C. If you lose disk B, you can work out what it was by using C - A. The problem with RAID 3, is that the parity disk gets overworked as data are written to it every time any data on the other disks are changed.

In RAID 5 the partity information is striped across the disks too. So you get the resiliance of RAID 3, but without the excess activity on one disk.

RAID 5 is great if you have a SCSI bus and lots of drives. It is the best performance reliable disk set up, but you need a lot of disks to get the best from it. Data recovery can also be slow if a disk fails (by the way, if two disks fail, you lose the lot again).

 

That's why I always try to include a hot spare in the budget. If 2 fail your still ok.

 

As long as your controller recognises the hot spare! However, yes you are right. A hot spare is always a good idea.

The other thing that is often over-looked is the monitoring system. I've seen a number of systems where a disk has failed but the users/admins don't realise it has. Then the second disk fails ........

You can spot a failed disk in a server room: drop in performance, lots of disk activity, but it's easy to miss. Much better to have a system that sends you a message if the RAID fails.

 

Raid 5 with a hot spare is def. a great investment if you're running a files server etc., but from the original post this is your personal equiptment correct? If so you will find that the setup will cost an arm and a leg. The controller alone is starts at $300+ and goes up to over $1,000.

 

How often do I get a chance to wax lyrical about different RAID configurations?

Yes, as stated earlier RAID 1 is the best option to answer the original post, but I'd like to think this is a more interesting discussion thanks to the musings on other options.

 

Promise TX4310

Cost-effective RAID 0/1/5/10 controller with SATA 3Gb/s drive support for motherboards with a PCI interface.

I paid 139.00 plus shipping on E Bay. Retail boxed with PAM utility.